Renal extracellular matrix alterations in lead-treated rats.

Although the nephrotoxic effects of lead are well documented, the subcellular mechanisms of its action on the kidney remain unclear. The aim of the present work was to investigate the effects of chronic lead exposure on the expression of laminin-1 and fibronectin in the kidney of lead-treated rats. Western immunoblotting of the kidney extracts revealed that experimental exposure to lead resulted in a marked decrease in the intensity of the bands corresponding to laminin-1 and an increase in the intensity of the band corresponding to fibronectin. Immunohistochemical studies demonstrated a weak labelling to laminin-1 and a strong labelling to fibronectin in all renal basement membranes together with a decrease in their thickness. Other ultrastructural alterations found were a diminution in the amount of endothelial fenestrae, an increased fusion of foot processes in epithelial cells of the glomerulus and the presence of intranuclear inclusion bodies in the proximal tubule cells. Lead intoxication might be responsible for the above alterations in the renal extracellular matrix that could play an important role in the pathogenesis of lead nephropathy.